The present invention relates to continuous polyester filaments in tufted form available for composing quality carpets featuring incomparable uniformity of appearance.
Reflecting significant growth of synthetic filaments in these years, a variety of synthetic filaments have established overwhelming share in the composition of modern carpets by replacing traditional woolen carpets. From the viewpoint of physical and performance characteristics, these synthetic filaments are more suited for the composition of carpets than conventional woolen carpets, and yet, costwise advantage over wool accounts for the sharply increased share of those synthetic filaments in the production of carpet today. In particular, total output of polyester filaments has achieved an extremely high level, and yet, by virtue of decreased production cost and quite satisfactory hand, polyester filaments entertain vast potentials for the composition of carpets.
By virtue of similarity to wool, synthetic staple fibers have long been made available for the composition of carpets. Those carpets composed of these synthetic staple fibers make littile difference from wool, thus providing much advantage.
On the other hand, from the viewpoint of productive efficiency, any of those conventional methods of manufacturing synthetic filaments available for composing carpets is by no means reasonable. Concretely, originally, synthetic fibers are produced in the state of continuous filaments, production of staple fibers results in costwise disadvantage because it compulsorily involves additional processes including cutting and spinning operations.
When manufacturing yarns from continuous synthetic filaments for the composition of carpets, manufacturers are obliged to provide those synthetic yarns with curling process. This is because a large amount of synthetic yarns are needed when producing a carpet by applying those synthetic yarns devoid of curled effect, and yet, because of insufficient bulkiness of tufted yarns, such a large amount of synthetic yarns are needed. Furthermore, those tufted yarns merely contain poor cushioning property and resiliency.
On the other hand, although the curling process for continuous synthetic filaments can be executed at inexpensive cost, those carpets composed of curled continuous synthetic filaments often generate specific defect that is rarely formed on those carpets composed of spun yarns. In particular, this defect is frequently generated in tufted carpets. Concretely, those domains containing varied luster and shades streakily appear in parallel with the running direction of needles.
On the other hand, by virtue of satisfactory mechanical property, durability, hand, and shade characteristic, and yet, owing to relatively low cost, polyester filaments and yarns are usefully made available for a wide variety of clothes and industrial goods.
Availing of distinctly satisfactory processability of polyester filaments and yarns, synthetic-fiber manufacturers have successfully improved quality of polyester filamets and yarns to be compatible with a wide variety of uses, thus gradually strengthening competitive potentials against all other synthetic fibers available today.
Polyester filaments proved to be quite satisfactory in quality for the composition of carpets. On the other hand, since polyester filaments contain such a specific gravity more than that of nylon or polypropylene or natural fiber like wool available for composing carpets, polyester filaments are slightly short of covering property when being made available for the superficial yarns of carpets.
To solve this problem, conventionally, the amount of superficial yarns is increased on condition that low-price polyester filaments are made available.
In order to provide sufficient covering property, manufacturers of polyester filaments available for composing carpets follow up improvement of covering property by deforming circular section of polyester filaments, method of contracting the process for deforming circular section of polyester filaments, and also a method of implementing these processes by achieving cost reduction. Not only for rationalizing production method, but the scope of cost reduction also involves saving of man-power and further decrease of the price of raw material. Nevertheless, actually, production of polyester fiber is underway at an accelerated operating efficiency, and yet, production of polyester fiber on a large package basis is also underway at a faster operating efficiency. In consequence, actually, further promotion of man-power saving can no longer yield substantial effect of cost reduction. Likewise, since the scope of the production of polyester fiber has fully been expanded today, even though the production scope may be expanded furthermore, it is quite difficult for all the concerned to sharply decrease the price of raw material below the present level. Furthermore, all the concerned can hardly orient the direction to follow up development of novel methods to achieve further cost reduction.
Recently, those plastic debris collected from scrap of molded products attract attention of the concerned. Relative to sharp growth of polyethylene terephthalate (PET) film and bottles in these years, a vast amount of plastic debris can potentially be procured for recycled use. Nevertheless, there are a wide variety of collectable plastic debris, and yet, quality of collectable plastic debris is noticeably variable. Therefore, unless selectively collecting a single kind of plastic debris, these collectable plastic debris cannot be made available for those objects subject to dyeing process. In particular, those plastic debris are not taken to be ideal for the raw material for composing filaments like bulky continuous filaments (BCF) containing curled property.
Even though collected debris of polyethylene terephthalate molded products may slightly incur transmutation of quality on the way of collection, owing to satisfactory fiber-forming property, it is not probable that production of filaments involves difficulty. On the other hand, conventionally, a variety of metamorphosing processes are applied to polyethylene terephthalate resin in order to improve film-forming property and molding property, and therefore, when transforming collected plastic debris into filaments, a variety of undesired properties are generated. For example, in order to facilitate molding operation, a substantial amount of diethylene glycol (GED) is copolymerized with resin available for executing a blow-molding process. Therefore, even when the blow-molded resin is transformed into filaments, the yeilded filaments incur yellowing symptom or sharply lowered lightfastness on exposure to light. In order to eliminate toxicity of aldehyde, it is imperative for such resin available for composing beverage/food bottles to minimize residual content of aldehyde. Therefore, it is preferred to use such resin containing a substantial amount terminal radical of carboxyl rather than the one containing a substantial amount of terminal radical of glycol that easily generates aldehyde. Nevertheless, after transforming collected resin into fibers, carboxylic terminal radical promotes thermal ageing effect.
On the other hand, since regenerated polyester resin is subject to re-melting process on the way of collecting process, the melted polyester resin is easily transmuted to result in the lowered limiting value of viscosity and the increased amount of carboxylic terminal radicals, thus eventually degrading own physical properties of the regenerated polyester resin.
In particular, the lowered limiting value of viscosity degrades tensile strength of fibers. When the regenerated polyester filaments are introduced for composing carpets incurring strong friction, carpet yarns quickly turn into fibrils during service. Once those fibrils are generated, dust easily deposits on the surface of the carpet to quickly stain the whole surface, and yet, these fibrils diminish depth of dyed shades to visually misgive users as though lightfastness is lowered.
It has long been pointed out that conventional carpets build more amount of static electricity in human bodies walking on the carpet than that is generated by other materials laid on floor. Since air-conditioning system has extensively been made available in modern life, the indoor environment tends to be short of moisture content, and thus, generation of static electricity is critical problem to solve. To properly solve this problem, a variety of useful methods have been introduced, for example, an art to coat the surface of component yarns with conductive resin and an art of blending conductive fibers with those component fibers composing a carpet, or the like. Although any of these useful methods proved to be quite effective, introduction of these methods raises the production cost of carpets, and yet, generally speaking, the effect of preventing static charge from occurence is not durable.